Lippmann diagrams: Theory and application to carbonate systems

Since 1980 when F. Lippmann's seminal paper appeared, our understanding of solubility equilibria involving ionic solid solutions has been advanced by theoretical considerations as well as careful experimental studies designed to determine excess Gibbs functions. A unified theory of solid-solution aq ueous-solution equilibria as well as the thermodynamic background of the ph enomenon of "stoichiometric saturation'' are reviewed. It is shown that Lippmann diagrams effectively summarize the thermodynamic basis of solid-solute aqueous-solution equilibria of sparingly soluble meta l carbonate systems. Clearly, the predictive power of these diagrams may be limited due to kinetic restrictions. Only when dissolution and precipitati on are essentially reversible, favourable conditions to synthesize homogene ous solid phases can be derived from studies of equilibria.